# The experimental probability of randomly choosing a red ball from a bag filled with red and blue is 75%. if there are 4 blue balls in the bag, how many red balls are there?

Feb 19, 2018

Number of Red balls $= 12$

#### Explanation:

Given -

Probability of taking one red ball is =75%=0.75
Number of Blue balls $= 4$
Number of Red balls =?
Probability of taking one red ball is$=$Number of Red Balls\/(Number of Red balls + Number of Blue balls)

Let Number of Red Balls $= x$

$0.75 = \frac{x}{x + 4}$
$\frac{x}{x + 4} = 0.75$
$x = 0.75 \left(x + 4\right) = 0.75 x + 3$
$x - 0.75 x = 3$
$0.25 x = 3$
$x = \frac{3}{0.25} = 12$
Number of Red balls $= 12$